Rich Ringel, M.D.
As far as pediatric cardiologist Richard Ringel is concerned, aortic coarctation, a narrowing of the major artery that carries blood out of the heart, is an enemy not easy to defeat. Many newborns with the problem show symptoms in the first few weeks of life, spurring surgical repair to restore normal blood flow to the aorta and vessels throughout the body. Most of these patients quickly get better but in about 15 percent of cases the narrowing returns, typically during growth spurts in the middle or high-school years. But in such cases, Ringel notes, many surgeons are not anxious to operate a second time.
“There’s a lot of scar tissue that’s hard to mobilize, and an increased risk of causing injury to the surrounding area,” Ringel says. “Surgeons often have to place a tube graft bypassing the narrowed area of the aorta.”
Many patients with aortic coarctation who were missed in early childhood, or with a slowly developing narrowing, are also detected around adolescence, necessitating surgical repair. As a less-invasive alternative for these patients, pediatric interventional cardiologists like Ringel offer a catheter approach in which they dilate the narrowed portion of the aorta with a balloon and then place a stent to keep it open while the aorta heals. But the stent itself, along with the anatomy of the patient’s aorta, occasionally can pose problems, They’re at risk of fracturing, causing the formation of aneurysms and, in worst cases, life-threatening aortic dissection – bleeding along the wall of the major artery – or rupture of the aorta.
“We’re talking about an area of the aorta that is narrow, and we’re expanding it under the assumption that all will go well,” Ringel says. “Unfortunately, once in a rare while the aorta will just tear instead of stretch and expand. Now you’re standing there with a torn aorta and blood leaking into the chest.”
The answer, Ringel notes, lies in the development of safer stents. Currently there is no FDA-approved stent for aortic coarctation, he explains, and those most often used are biliary stents designed to treat obstructions in the bile ducts. While “not completely unhappy” with these off-label stents, Ringel believes the risks of stent-related complications can be reduced and patient outcomes improved with new devices. That’s why he’s leading a clinical trial of a new bare metal stent involving 105 patients at 19 medical centers. Outcomes of the Coarctation Of the Aorta Stent Trial (COAST) will be determined by the difference in arm-leg systolic blood pressure over 12 months after the intervention, as well as stent-related complications like fractures.
“This device is stronger and shortens less when you expand it,” Ringel says. “We’re hoping it will have a lower fracture rate.” Also unique to this trial is that all participating centers have a version of this stent with a fabric covering that can be used immediately to repair an aortic wall injury discovered before the procedure or occurring as a result of the stent. Ringel is also enrolling patients in a multi-center trial of these “covered” stents. These stents in particular, Ringel stresses, may offer the most promise for patients at risk of aortic aneurysms, dissection or rupture.
“We’ve had multiple patients already whose lives were saved or who avoided major open heart surgery after rupture of their aorta,” Ringel says. “These really are potentially life-saving devices.”
For more information, call 410-614-6745, or visit The Helen B. Taussig Congenital Heart Center at Johns Hopkins.